The TIOBE authors found no obvious reason why interest in F# is continuing to rise, at least by their measure. They offered up recent promotional efforts by the F# Software Foundation as one possible reason. Last fall, a number of major improvements to the language and to the Visual F# Tools were announced, which could also help explain some of the increased interest.

Whatever the reason for what TIOBE is seeing, I decided to see if an increase in F# interest was reflected in other measures of programming language popularity and usage. First, I looked to the latest PYPL index, also for March, which ranks languages based on Google searches for language tutorials. F# is not among the 16 languages they ranked. However, using Google Trends, which is what the PYPL authors use to generate their rankings, you can see that interest in F# has overall, fluctuated up and down around roughly the same level for the last four years.

Finally, I looked at where F# ranks among languages used in GitHub repositories. GitHut provides a nice interface for comparing languages based on (among other things) the number of active repositories. For the latest quarter, Q4 2014, F# ranked 44th among languages in terms of active repositories, just ahead of Elixir (45th) and behind Julia (43rd). F#’s share of the overall number of active GitHub repositories was up in Q4 2014 (.055%) over Q4 2013 (.048%), which was up slightly from one year before that (.041% in Q4 2012).

Looking at these results as a whole, the trends indicate that usage and popularity of F# is generally trending upwards, although at a slow rate. TIOBE’s findings that it’s (almost) a top ten language, however, seem to be the outlier. By most other metrics, F# is still a middle-of-the-pack language, though better days might eventually be coming.